BoilerFaultCodesTechnical description
Burner control switches to lockout
What causes this fault?
This fault occurs when the boiler's internal safety sensors detect that the gas pressure is either too low or fluctuating, preventing the burner from staying lit. It is often caused by a failing gas valve that can't regulate the flow properly or worn ignition electrodes that are struggling to spark. In some cases, the main control board has developed a communication error and can no longer safely manage the combustion process.
This fault can be more frequent during extreme cold snaps when high local demand for gas can cause drops in mains pressure, or when debris in the gas line settles during the first heavy use of the winter.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.